1. Classification of contactors:
● According to the different voltage of the control coil, it can be divided into: DC contactor and AC contactor
● According to the operation structure, it is divided into: electromagnetic contactor, hydraulic contactor and pneumatic contactor
● According to the action mode can be divided into: direct motion contactor and rotary contactor.
2. Electromagnetic contactor
● Role and classification of the contactors
Electromagnetic contactor is the control circuit that uses the main contact to close or break the motor circuit or the load circuit of other functions. It can achieve frequent long-distance operation, it has several times larger than the working current or even ten times the switching and breaking ability, but can not break the short circuit current. Because of its small size, low price and easy maintenance, it is of wide use. The main use of the contactor is to control the start, reversal, speed regulation and braking of the motor. It is the most important and the most commonly used control electrical appliance in the electric drag control system.
According to the form of the main contact connection loop, it is divided into direct contactor and AC contactor.
According to the operation mechanism, it is divided into: electromagnetic contactor and permanent magnet contactor.
According to the number of poles of the main contact (i. e., the number of main contacts), the DC contactors are unipolar and bipolar; the AC contactors have three poles, four poles and five poles.
● Working principle of the contactor
When the AC contactor coil is energized, a magnetic flux is generated in the iron core. Therefore, the suction is generated in the armature gap, making the armature produce a closing action, and the main contact is closed by the armature, so the main circuit is connected. At the same time, the armature also drives the auxiliary contact movement, making the original open auxiliary contact closed, and opening the original closed auxiliary contact. When the coil is powered off or the voltage is significantly reduced, the suction disappears or weakens, the armature is opened under the action of the release spring, and the main and auxiliary contacts are restored to the original state.
The contactor uses the main contact to break the main circuit, and the auxiliary contact to break the control loop.
Post time: Mar-17-2023
